From 8838ca560032990d23d62a67cf9b38caaa02e8dc Mon Sep 17 00:00:00 2001
From: Gauri Joshi <gaurjosh@codeaurora.org>
Date: Mon, 10 May 2021 23:59:29 -0700
Subject: [PATCH] msm: mhi-dev: Add support for AIO write API

Diag client uses asynchronous writes for data transfer.
Adding write_iter API in mhi to support the same.

Change-Id: If14ebdd4aa848046abd15ea93d939691c6962fcd
Signed-off-by: Gauri Joshi <gaurjosh@codeaurora.org>
---
 drivers/platform/msm/mhi_dev/mhi_uci.c | 63 ++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/drivers/platform/msm/mhi_dev/mhi_uci.c b/drivers/platform/msm/mhi_dev/mhi_uci.c
index 3a69f9359b45..2d04c2cbf5b0 100644
--- a/drivers/platform/msm/mhi_dev/mhi_uci.c
+++ b/drivers/platform/msm/mhi_dev/mhi_uci.c
@@ -8,6 +8,7 @@
 #include <linux/cdev.h>
 #include <linux/wait.h>
 #include <linux/uaccess.h>
+#include <linux/uio.h>
 #include <linux/slab.h>
 #include <linux/poll.h>
 #include <linux/sched.h>
@@ -424,6 +425,8 @@ static ssize_t mhi_uci_ctrl_client_read(struct file *file, char __user *buf,
 		size_t count, loff_t *offp);
 static ssize_t mhi_uci_client_write(struct file *file,
 		const char __user *buf, size_t count, loff_t *offp);
+static ssize_t mhi_uci_client_write_iter(struct kiocb *iocb,
+					 struct iov_iter *buf);
 static int mhi_uci_client_open(struct inode *mhi_inode, struct file*);
 static int mhi_uci_ctrl_open(struct inode *mhi_inode, struct file*);
 static int mhi_uci_client_release(struct inode *mhi_inode,
@@ -1480,6 +1483,65 @@ error_memcpy:
 
 }
 
+static ssize_t mhi_uci_client_write_iter(struct kiocb *iocb,
+					 struct iov_iter *buf)
+{
+	struct uci_client *uci_handle = NULL;
+	void *data_loc;
+	unsigned long memcpy_result;
+	int rc;
+	struct file *file = iocb->ki_filp;
+	ssize_t count = iov_iter_count(buf);
+
+	if (!file || !buf || !count || !file->private_data) {
+		uci_log(UCI_DBG_DBG, "Invalid access to write-iter\n");
+		return -EINVAL;
+	}
+
+	uci_handle = file->private_data;
+	if (!uci_handle->send || !uci_handle->out_handle) {
+		uci_log(UCI_DBG_DBG, "Invalid handle or send\n");
+		return -EINVAL;
+	}
+	if (atomic_read(&uci_ctxt.mhi_disabled)) {
+		uci_log(UCI_DBG_ERROR,
+			"Client %d attempted to write while MHI is disabled\n",
+			uci_handle->out_chan);
+		return -EIO;
+	}
+
+	if (!mhi_uci_are_channels_connected(uci_handle)) {
+		uci_log(UCI_DBG_ERROR, "%s:Channels are not connected\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	if (count > TRB_MAX_DATA_SIZE) {
+		uci_log(UCI_DBG_ERROR,
+			"Too big write size: %lu, max supported size is %d\n",
+			count, TRB_MAX_DATA_SIZE);
+		return -EFBIG;
+	}
+
+	data_loc = kmalloc(count, GFP_KERNEL);
+	if (!data_loc)
+		return -ENOMEM;
+
+	memcpy_result = copy_from_iter_full(data_loc, count, buf);
+	if (!memcpy_result) {
+		rc = -EFAULT;
+		goto error_memcpy;
+	}
+
+	rc = mhi_uci_send_packet(uci_handle, data_loc, count);
+	if (rc == count)
+		return rc;
+
+error_memcpy:
+	kfree(data_loc);
+	return rc;
+}
+
 void mhi_uci_chan_state_notify_all(struct mhi_dev *mhi,
 		enum mhi_ctrl_info ch_state)
 {
@@ -1877,6 +1939,7 @@ static const struct file_operations mhi_uci_ctrl_client_fops = {
 static const struct file_operations mhi_uci_client_fops = {
 	.read = mhi_uci_client_read,
 	.write = mhi_uci_client_write,
+	.write_iter = mhi_uci_client_write_iter,
 	.open = mhi_uci_client_open,
 	.release = mhi_uci_client_release,
 	.poll = mhi_uci_client_poll,